Field of the Invention
The present invention relates to novel subtilase variants exhibiting increased stability and optionally on par or improved wash performance. The variants of the invention are suitable for use in e.g. cleaning or detergent compositions, such as laundry detergent compositions and dish wash compositions, including automatic dish wash compositions. The present invention also relates to isolated DNA sequences encoding the variants, expression vectors, host cells, and methods for producing and using the variants of the invention.
Description of the Related Art
In the detergent industry, enzymes have for many decades been implemented in washing formulations. Enzymes used in such formulations comprise proteases, lipases, amylases, cellulases, mannosidases as well as other enzymes or mixtures thereof. Commercially the most important enzymes are proteases.
An increasing number of commercially used proteases are protein engineered variants of naturally occurring wild type proteases Everlase®, Relase®, Ovozyme®, Polarzyme®, Liquanase®, Liquanase Ultra® and Kannase® (Novozymes A/S), Purafast®, Purafect OXP®, FN3®, FN4® and Excellase® (Genencor International, Inc.). Further, a number of variants are described in the art, such as in WO2004/041979 (Novozymes A/S) which describes subtilase variants exhibiting alterations relative to the parent subtilase in e.g. wash performance, thermal stability, storage stability or catalytic activity. The variants are suitable for use in e.g. cleaning or detergent compositions.
A number of useful subtilase variants have been described many of which have provided improved activity, stability, and solubility in different detergents. For example, WO 2007/006305 describes a list of variants comprising the substitution N261 D in combination with a number of other substituents but not in combination with a modification of position 194. EP516200 describes the substitution of position 194 but not in combination with a modification in position 261.
However, various factors make further improvement of the proteases advantageous. The washing conditions such as temperature and pH changes over time and many stains are still difficult to completely remove under conventional washing conditions. Further, in wash conditions can result in inactivation of the enzymes (due to e.g. pH, temperature or chelation instability) resulting in loss of wash performance during the wash cycle. Thus despite the intensive research in protease development there remains a need for new and improved proteases that have improved stability, in particular improved in wash stability, and preferably similar or improved wash performance compared to the parent subtilase.